RE: VAJ and Compiler Options

["Larry Loen" <lwloen@xxxxxxxxxx>]

>Oh, that.  My Sun documentation for javac says this:

>"Note: the -O option does nothing in the current implementation of javac
and
>oldjavac."

>VAJ uses an IBM compiler and not Sun's, it's true.  Maybe it doesn't do
>optimization either?  I don't know.

AFAIK, it was never very important.  Javac never was a full-fledged
optimizing compiler and does not need to be because IBM (and, to give the
devil their due, Sun) have made the appropriate investments in the JIT
technology (and, in OS/400's case, the added opportunities from the
transformer).

The genius of the Java Virtual Machine is that byte codes (and class files
in particular) are really compiler intermediate text (yet interpret well).

So, anyone can apply further optimizations to any sort of compile/JIT
process based on the bytecodes.  Even the compiler symbol table type
information is present.  Thus, javac's output need not be extensively
optimized.


Larry W. Loen  -   Senior Linux, Java, and iSeries Performance Analyst
                          Dept HP4, Rochester MN